A program of research has been undertaken to investigate the dissolution of language comprehension in the aphasias and related cognitive disorders. An approach has been designed in which the semantic domain is held constant across a variety of tasks that test comprehension of several morphological, syntactic and semantic variations within that restricted semantic domain. This procedure provides detailed profiles of comprehension abilities for a large number of patients with a variety of symptoms and lesion sites. This information is used to identify the components of comprehension which can be impaired conditions of focal brain damage. The emphasis in this investigation is on the pattern of dissolution of the retrieval and representation of lexical meaning and the construction and representation of sentential meaning. A central concern is the identification of the component processes that underlie the construction of sentential meanings in comprehension. A basic contention motivating the project is that the cognitive processes involved in the comprehension of lexical items and larger semantic units (phrases and sentences) can be differentially affected by focal brain damage.